<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .wrap{
            width: 300px;
            height: 300px;
            border: 1px solid;
            background: pink;

            position: absolute;
            left: 0;
            right: 0;
            top: 0;
            bottom: 0;
            margin: auto;
        }
        .inner{
            width: 200px;
            height: 200px;
            border: 1px solid;
            background: gray;

            position: absolute;
            left: 0;
            right: 0;
            margin: auto;
        }
        .app{
            width: 100px;
            height: 100px;
            border: 1px solid;
            background: hotpink;

            position: absolute;
            left: 0;
            right: 0;
            bottom: 300px;
            margin: auto;
        }
    </style>
</head>
<body>
    <div class="wrap">
        <div class="inner">
            <div class="app"></div>
        </div>
    </div>
</body>
<script>
    window.onload=function (){
        var wrap = document.querySelector(".wrap")
        var inner = document.querySelector(".inner")
        var app = document.querySelector(".app")


        wrap.addEventListener("mouseover",()=>{console.log("wrap over")})
        wrap.addEventListener("mouseout",()=>{console.log("wrap out")})

        inner.addEventListener("mouseover",()=>{console.log("inner over")})
        inner.addEventListener("mouseout",()=>{console.log("inner out")})

        app.addEventListener("mouseover",()=>{console.log("app over")})
        app.addEventListener("mouseout",()=>{console.log("app out")})
    }
</script>
</html>